Fourdrinier machine belt



April 4, 1961 H. M. HELLAND FOURDRINIER MACHINE BELT Filed NOV. 14, 1958 JNVENTOR.

HOWARD M. HELlA/VD BY:

United States Patent 9 a 2,978,023 FOURDRINIER MACHINE BELT Howard M. Helland, Newfane, N.Y., assignor to Lockport Felt Company, Inc., Newfane, N.Y.

Filed Nov. 14, 1958, Ser. No. 774,025

3 Claims. (Cl. 162-348) Under modern paper making conditions such belts are called upon to train around a constantlyincreasing number of rolls, and at greatly increased speeds. Hence, belts which previously would function satisfactorily and stand up for normal periods of use on older types of machines are deficient when used in .the modern machines, because of their structural weaknesses, tendencies to clog and become inefficient as drainage devices, and their vulnerability to fatigue destruction due to the flexing of the belt around the greater number of rolls at the highly increased speeds referred to.

Some attempts have been made to provide the necessary increased strength and flexibility to meet these more rigorous conditions, such as by Weaving the belts of heavier sized wires and by reducing the weft count, but with the result that the mesh openings became undesirably larger. Thus, the paper formation surface of the belt is of correspondingly increased roughness, producing an undesirably rough paper surface. Also, in such cases there is "a tendency of the pulp fibres to turn down and become locked in the mesh openings of the belt thereby plugging the belt interstices and rendering it inefiicient as a drainage medium.

It is of course well known in the art to be highly desirable to provide a belt which will have a maximum area of we..r surfaces, and yet will be of optimum flexibility in the longitudinaldirection of the cloth.' Also, the belt should be as free as possible from fatigue flexing,

and should present a support surface on which the paper formation will be held flat as possible, while at the same time providing an adequate drainage facility. Thus, it is a primary object of the present invention to provide a wire belt having the aforesaid and other desirable characteristics; and by way of exemplification, a belt construction of the invention is illustrated in the drawings herewith, wherein:

Fig. 1 is a schematic side elevational view of a As shown in Fig. l, a belt of the invention is indicated I which the paper pulp feeds onto the belt 10 as indicated at 14. Typically, table rolls as indicated at 16 are pro- Patented Apr. 4, 1961 vided to support the belt in level horizontal attitude during its initial travel away from the head box. During this phase of the belt movement water drains from the pulp through the interstices of the belt, and is caught in a launder or the like as indicated at 18. The belt next passes over a suction box as indicated at 20 whereat a suction effect is provided to extract additional moisture from the pulp not previously eliminated by the gravity drainage action, as is customary in this type of machine.

The belt then traverses a guide roll as indicated at 22 and thence trains around a so-called couch roll 24 at which point the pulp layer is picked 01f as indicated at 25 before the belt commences the return phase of the belt motion cycle. Customarily it next traverses an idler roll 26, and then a belt tension adjustment roll 28 from whence it trains around another idler roll 30 and finally around a breast roll 32 located just ahead of the head box 12. Power driving the belt to travel throughout the system hereinabove described is supplied to the couch roll. Thus it will be appreciated that due to the drag of the suction box 20 against the travel of the belt, the belt will be under maximum longitudinal tension between the positions of the suction box 20 and the couch roll 24; while being in relatively relaxed condition as it is delivered from the couch roll and commences the return phase of the belt travel cycle. As a consequence, longitudinally successive increments of the belt structure are alternately subjected to maximum and minimum tension loadings as they approach and pass around the couch roll.

Broadly stated, the present invention contemplates provision of an improved belt construction whereby the above described differential tension action is availed of to induce an improved self-cleaning action within the belt structure per se. Also, the structure comprises a novel filament weave system whereby the belt, throughout the pulp supporting phase of the-belt travel cycle, provides a substantially smooth pulp supporting surface. Furthermore the filament weave pattern is such as to provide a belt of improved longitudinal strength, and filament crossover knuckles of less abrupt'shapes and reduced elevations resulting in reduced angle of impact effects compared to woven belts of the prior art. Also, the construction provides an inherently stable running belt; that is, a belt in which the longitudinal tension forces are balanced laterally, whereby the belt does not tend to pull to one side as it traverses the Fourdrinier machine rolls.

As shown for example in Figs. 2-4, the belt of the I invention may be woven of a plurality of like filaments designated 35, which are formed of any suitable material such as metal, synthetic or natural plastic, fibrm, or the like, or composites thereof; the requisite being that they have suitable flexibility and resiliency characteristics, as will be explained more fully hereinafter. As shown in the drawing, the filaments are disposed in substantially side-by-side inter-braided relation; each filament running longitudinally of the belt while deviating from a straight line path alternately in opposite directions and intertwining thereat with the opposite next adjacent filaments. Thus, as shown in Fig. 3, when the belt is relaxed the re- .si-liencies of the individual filaments cause the latter to spring apart somewhat; thereby providing relatively open interstices as indicated at 36. However, when the belt is under longitudinal tensioning as explained hereinabove, the strands 35 are substantially straightened as shown in Fig. 2, while the interstices therebetween are substantially closed whereby the belt presents a substantially smooth surface to the pulp being supported thereon.

Thus, as mentioned hereinabove, as each increment of the belt moves into position between the suction box 20 and the couch roll 24, it is under maximum tension and in the condition illustrated by Fig .2, whereby the filaments 35 are disposed in substantially straight line form longitudinally of the belt, thereby contributing maximum strength per over-all weight of filaments. Furthermore, the weave structure is such that it is adapted to flex and travel around the rolls of the machine with maximum facility while experiencing minimum internal working of one filament against another; and minimum impact shocks of the weave knuckles against the machine rolls or other belt contacting accessories.

Then, as the belt increment travels rearwardly away from the couch roll, the longitudinal tension in the belt structure is relaxed, permitting the belt to laterally expand as explained hereinabove into a condition such as is illustrated by Fig. 3. Thus, the belt structure is constantly expanding and contracting laterally as it moves toward and away from the couch roll in such a manner as to provide an optimum pulp support when needed and automatic self-cleaning of the belt structure pores when not supporting pulp. Similarly, due to the novel construction of this Fourdrinier belt, it responds in improved manner to use of spreader and/or contracting rolls, such as may be employed in the Fourdrinier machine, whereby additional self-cleaning effects may be obtained. Water sprays or the like as indicated at 38 may be employed to assist in the dislodgement and flushing away of particles previously entering and tending to plug the intersticcs of the belt weave.

Whereas the Fourdrinier belt illustrated and described herein comprises one specific interlocking pattern form, the filaments thereof may be interlocked in any other pattern; the belt structure of the invention being characterized by the fact that all of the filaments run longitudinally of the belt and no transverse filaments are involved.

Thus, although only one form of the invention has been shown and described in detail, it will be apparent to those skilled in the art-that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a Fourdrinier machine, a belt therefor comprising a plurality of filaments having inherent resilient characteristics and each running substantially longitudinally of the belt in side-by-side relation and periodically deflecting in opposite directions and interlocking alternately with other filaments, said machine being arranged to subject the paper pulp carrying run of the belt to increased tension whereby the belt filaments are drawn together laterally to provide a substantially closed surface for support of the pulp, while the return run of the belt is subjected to lesser tension so that it expands laterally thus causing the filaments to move apart thereby forming openings facilitating abstraction of retained pulp from the belt.

2. In a Fourdrinier machine, a belt therefor comprising a plurality of filaments having inherent resilient characteristics and each running substantially longitudinally of the belt and periodically deflecting in opposite directions and braiding alternately with other filaments, said machine being arranged to subject the paper pulp carrying run of the belt to increased tension whereby the belt filaments are drawn together laterally to provide a substantially closed surface for support of the pulp, while a portion of the return run of the belt is subjected to lesser tension so that it expands laterally thus causing the filaments to move apart thereby forming openings facilitating abstraction of retained pulp from the belt.

3. In a Fourdrinier machine, a belt therefor comprising a plurality of filaments having inherent resilient characteristics and each running substantially longitudinally of the belt but braided together to form a substantially flat web, said machine being arranged to subject the paper pulp carrying portion of the belt to increased tension whereby the belt filaments are snugged together to provide a substantially smooth closed surface for support of the pulp, while at least a portion of the return portion of the belt is subjected to lesser tension so that it expands laterally thus causing the formation of openings between the filaments thereby facilitating cleaning of the belt.

References Cited in the file of this patent UNITED STATES PATENTS 

